52
Coefficient of Permeability k (cm/s) (log scale)
10²
10¹
10
0
10
–1
10
–2
10
–3
10
–4
10
–5
10
–
6
10
–
7
10
–
8
10
–9
Drainage
Good
Poor
Practically impervious
Soil type
Clean
gravel
Clean sands,
clean sand
and gravel
mixtures
Very fine sands, organic and
inorganic silts, mixtures of
sand silt and clay, glacial till,
stratified clay deposits, etc.
“Impervious”
soils (e.g.,
homogeneous
clays below
zone of
weathering)
“Impervious” soils modified by effects
of vegetation and weathering
Direct
determi-
nation of
k
Direct testing of soil in its original
position – pumping test; reliable if
properly conducted; considerable
experience required
Constant-head permeameter;
little experience required
Indirect
determi-
nation of
k
Falling-head
permeameter;
reliable; little
experience required
Falling-
head
permeame-
ter
unreliable;
much
experience
required
Falling-head
permeameter; fairly
reliable; considerable
experience necessary
Computation from grain-size
distribution; applicable only to
clean cohesionless sands and
gravels
Computation
based on results of
consolidation
tests; reliable;
considerable
experience
required
Gambar 2.27 Interval Nilai Koefisien Permeabilitas
Tanah Berdasarkan Jenis
Tanah (Casagrande dan Fadum; 1940)
(Sumber: Soils and Foundations, Prentice Hall)
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